Each year many chimney fires occur and cause damage because accumulations of poorly burned combustion gases condense on the inside surfaces of chimney flues. These gases condense on flue surfaces cooled below 255 degrees F. forming a hard glaze coating that is extremely resistant to most cleaning techniques. Deposits of this type are not burnt and charred like soot, but instead they are hard, inflammable, and dangerous. This is the type of creosote deposit that ignites during a chimney fire and in doing so swells into a crusty, volumous material as it burns in a very hot and uncontrollable manner.
There is another type of deposit in chimneys that is more brittle and less inflammable so therefore, less dangerous as well. This type of creosote, or soot, is mostly found in areas of the chimney that are hottest, near to the combustion source. Soot and burned creosote can clog chimneys, but layers of it can be removed rather easily by less abrasive means then those necessary to remove glazed creosote layers.
Brush or scraping devices described by prior art can be adequate to effectively remove most soot but they can not remove hard glaze layers very effectively. Periodic cleaning with prior art methods unable to remove the more dangerous, hard creosote deposits can sometimes keep the chimney unclogged, but it does little or nothing to remove the dangerous deposits so they remain as does the potential for ignition and a chimney fire. If this is allowed to continue a steady buildup of glaze forms a thick, hard, and sometimes clumpy, deposit of creosote that can finally reduce conduction channel apertures enough to clog a chimney entirely. It has been our experience to observe this type of clog in chimneys that have been regularly cleaned with prior art brushing or scraping techniques. The only fortunate aspect of this condition is that no chimney fire has yet occured, but this is a very undesirable situation, one not so easy to avoid in some long chimneys that do not heat up much during use. Also undry wood and wood conservation measures such as slow burning in modern airtight stoves increases the likelihood for this to occur. These practices are more common than ever in recent years since wood burning, as a means to heat a home, is increasing in popularity because unstable and generally higher costs for fossil fuels have become reality. The chimney cleaner of this invention is designed to allow the homeowner to have at his disposal an easy and effective means to remove glazed creosote, even if regular chimney cleaning is forgotten from time to time and deposits get fairly thick, to be sure dangerous deposits can not accumulate and clog a chimney or worse yet ignite into a chimney fire.
Prior art described in the patent depository has many references relating to chimney flue cleaning, most of these devices utilize an embodiment or variant of either bristle or scraper elements to provide the cleaning means. Irrespective of how these cleaning devices are designed they possess disadvantages inherent to these basic cleaning elements. Both of these elements exhibit inadequate abrasive properties to remove creosote glaze. If cleaning devices using these elements as the cleaning means are used to clean a chimney only brittle soot and charred creosote deposits are effectively removed, leaving creosote glaze behind and further exposed to increased concentrations of oxygen and higher temperature levels that can even increase the possibility of ignition and the resulting chimney fire. The reason for this problem is clear; thin bristles made from a flexible material bend around obstacles (commonly encountered in chimney flues) very well but they provide only limited abrasive capability because of this flexibility, and scrapers do not have enough applied force (pressing them onto deposits), edge sharpness, or both, to penetrate and cut into the hard, glazed creosote deposits and remove it. Bristle ends scratch as they are forced onto and dragged across deposits, but they have limited ability to dig into and remove deposits because they (that contact deposits) are flexed behind, opposite to the direction of dragging during use. Even the wide, robust bristles of U.S. Pat. No. 4,254,528 by Souliere exhibit these disadvantages. Bristle hardness is also generally a problem with cleaning devices utilizing bristles. Spring steel, the usual material for bristles, is relatively hard but not hard enough to resist wear in part because they are usually thin and slender to remain flexible. Thin material wears away quickly, shortening the ends that abrade over deposits so the bristles become too short and dull to clean with peak effectiveness.
A notable exception to the disadvantages mentioned above is the device described in U.S. Pat. No. 4,470,168 by Vickey that uses axial force generated by wobbling motions created during device free-fall inside a flue to impact chisel-like bristles against deposits to penetrate and chip them. However, limited numbers of bristle members (protruding from this device) and the reliance on random impacts therefrom to chip and dislodge a massive coating of creosote make cleaning slow and unreliable. Furthermore, this gravity dependent design limits it to vertically orientated tubes like chimney flues.
Scraper elements are usually designed excessively large, spreading the outward force applied to them over a long, chisel-like cutting edge. The extent of penetration of a sharp object into a substance is, among other things, directly proportional to the force applied, and indirectly proportional to the size or length of the chisel-like edge. Other facters include scraper sharpness and the angle that the edge(s) contact these substances. The right combination of these properties is required or removal of a hard substance like glazed creosote will be minimal. A scraper that can not penetrate hard substances simply slides over hard creosote deposits as it is stroked across, doing nothing useful. In addition most cleaning devices using scraper elements as the cleaning means do not address wear, and techniques to minimize wear in their design. Dangerous creosote glaze is very hard and tightly stuck to the inner surfaces of some chimneys so very robust scraping elements with specially designed features that circumvent the problems described are necessary to remove it reliably. A means to replace scrapers when worn and construction from hardened, high carbon steel, forged into sharp edges especially constructed to take punishment and wear, are two properties absolutely essential to make an effective scraper.
The cleaning device described in U.S. Pat. No. 1,315,849 by MacDonald consists of scraper elements (cleaning means) made from long chisel-like edges mounted onto a complex mechanical arch made from serial end to end linkage of many steel members loosely joined to pivot. One end of this linkage is connected to a coil spring and the other is held stationary to compress and bend said linkage into an arch whereby scrapers are pressed against opposing flue surfaces. This is a very complex, cumbersome, and expensive linkage by todays standards. A weight and a chain provide the means to stroke this cleaning device to and fro inside a chimney. Even a modest magnitude of force applied to opposing scrapers can pinch this cleaning device inside the flue and halt it progress because the force of gravity on the weight used to provide the downward stroking means has practical limits in this or other gravity dependent designs. In our experience, penetration and removal of creosote glaze requires greater force then this gravity dependent design can offer, especially if the scrapers have long scraping edges as is the case with this device. This device can clean flat and curved surfaces so square and round flues can be cleaned, but only opposite surfaces can be cleaned simultaneously because it only has two opposing scrapers. Thus, the device operator must perform many position changes from a remote position during use to guide it around and completely clean all inner surfaces of the flue. This is a cumbersome task that requires time, patience, and practice to obtain adequate results.
More recent cleaning devices, while still employing bristle or scraper elements as the cleaning means, provide improvements in design to enhance creosote removal. The rather obvious improvements typical to modern cleaning devices are greater bristle stiffness, increased pressing or raking force applied to the cleaning elements, and sharper scrapers. These improvements have limitations and offsetting disadvantages. For example a cleaning device made with bristles of increased stiffness is harder to stroke and less apt to pass unyielding obstructions or offsets commonly found between flue sections so cleaning is incomplete. A scraper type chimney cleaning device must have a means to create force sufficient enough for the scrapers to function and still remain flexible enough to distort and pass obstructions to avoid hooking on them, a very difficult task for prior art designs.
Recent cleaning devices with U.S. Pat. No. 4,319,378 by Bowman et. al. and U.S. Pat. No. 4,353,143 by Beaudoin et. al. use decreased numbers of stiffened bristles and/or decreased overall device size to concentrate the cleaning effort on small discrete areas of inner flue surfaces at any one time. These cleaning devices are as a rule more effective in glaze removal, but not enough and they are slow, inconvenient, and difficult to use for reasons already discussed. The cleaning device by Bowman is complicated to construct; it has swivel and threaded journals to permit expansion of its size by handle rotation, and it requires many such remote adjustments and position changes that can be very difficult if the device is far into the flue. The brush-like cleaning device by Beaudoin, comprised of a few stiff bristles, has low bristle density so many reciprocating strokes are needed to scratch away a coat of creosote and the flexible unitary stroking means thereof easily allows pull strokes (toward the operator) but push strokes (away from the operator) are not easy in long flues that are clogged, especially if obstructions are present therein. Our experience indicates that these bristles will slide over and remove only brittle, loose deposits and leave the hard glaze behind because they are attached to a break mechanism whereby they fold behind the device and allow it to pass obstructions.
U.S. Pat. No. 4,333,200 by Thurow, U.S. Pat. No. 4,498,212 by Davis, and U.S. Pat. No. 4,492,000 by Skogen describe more recent cleaning devices that use scraper elements. These and all cleaning devices that use scrapers have a means to pres them onto deposits, but the usual long blunt edge on nonreplaceble scraper elements of these devices can not easily penetrate into hard glazed creosote. In addition patents by Skogen and Thurow illustrate devices that can only clean opposite surfaces, not all crossection surfaces of a flue simultaneously. The device described in the Davis patent can only scrape one small surface area of a flue at a time and must be moved often to clean other surfaces. Thus, both of these cleaning devices require many position changes, performed by the remote operator, to cover and clean all flue surfaces coated with creosote; both are slow and inconvenient to use, and the device described by Skogen can only clean uncurved surfaces (as illustrated) limiting its usefullness in round flues.
U. S. Pat. No. 1,293,777 by Hogue describes a device to clean round oil pipes. Sludge deposits clogging oil pipes, much different then hard creosote, are removed by an array of four bowed springs under rotation in combination with a liquid stream under pressure. Bowed springs of this invention also do not have separate or integral scraping means in any form attached thereon so they can not grind and scrape away typical hard deposits. Liquid is also undesirable in many cleaning chores so its applications are limited as a result.
Heretofore, with prior art cleaning devices or methods including improved devices of recent years, chimney flue cleaning remains a dirty, slow, and inconvenient job; thus, a need for a better apparatus to enable complete, quick, and easy chimney cleaning, while being durable, simple, and inexpensive to manufacture remains. This invention described in the following text is able to completely clean a chimney (or other hollow ware), removing hard and tightly stuck deposits like inflammable creosote that usually is left behind, unlike any prior art methods or cleaning devices to our knowledge.